High speed turbomachines can employ various types of bearings. For example, rolling element bearings, magnetic bearings, foil bearings or fluid film bearings can be employed.
Oil free turbomachines provide many benefits. For one, there are more effective heat transfer surfaces and no issues with oil stability or contamination. Oil free turbomachines have employed magnetic bearings, hydrostatic bearings, or foil bearings. Turbomachines have also been developed using refrigerant lubricated roller bearings and hydrostatic bearings.
Disadvantages of current turbomachines are the expense and complexity of the magnetic bearing, as well as scaling problems with foil bearings that makes large machines unfeasable. Additionally, the power consumption of hydrostatic bearings can be high, and when operated under high loads, the reliability of ball bearings can decrease.